2. Balance the following redox reactions in acidic medium. Cu (s) +NO 3(aq) ^ - +Cu (aq) ^ 2+ +NO (g) ) [By ion electron method]
Answers
Explanation:
ANSWER
The unbalanced redox equation is as follows:
Cu+NO
3
−
→Cu
2+
+NO
2
All atoms other than H and O are balanced.
The oxidation number of Cu changes from 0 to 2. The change in the oxidation number of Cu is 2.
The oxidation number of N changes from 5 to 4. The change in the oxidation number of N is 1.
The increase in the oxidation number is balanced with decrease in the oxidation number by multiplying NO
3
−
and NO
2
with 2..
Cu+2NO
3
−
→Cu
2+
+2NO
2
O atoms are balanced by adding 2 water molecule on RHS.
Cu+2NO
3
−
→Cu
2+
+2NO
2
+2H
2
O
To balance H atoms, add 4 H
+
on LHS.
Cu+2NO
3
−
+4H
+
→Cu
2+
+2NO
2
+2H
2
O
Since the reaction occurs in basic medium, add 4 hydroxide ions on both sides of the equation.
Cu+2NO
3
−
+4H
+
+4OH
−
→Cu
2+
+2NO
2
+2H
2
O+4OH
−
On LHS, 4 H
+
ions combine with 4 OH
−
ions to form 4 water molecules out of which 2 water molecules cancel out with 2 water molecules on RHS.
Cu+2NO
3
−
+2H
2
O→Cu
2+
+2NO
2
+4OH
−
This is the balanced chemical equation.